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When the car is in gear and idling it makes a thumping/knocking sound, not like a rod or anything, but a rhythmic thumping. It makes this sound until about 1000RPM's I'd guess.

I haven't driven my Civic much, and it's still has some of the gas in it from when I bought it (had been sitting for a few months), but I have added $20 of premium since then.

I changed the oil, and there was no difference. Checked all the fluids and they're fine.

It's most noticeable from INSIDE the car, I couldn't really hear anything from the outside. Sounds kinda like a misfire, but I know the engine is firing on all cylinders.

The plugs and plug wires are from 2004.

Valves? Ignition? I just ordered new plugs and wires, gonna see if that changes anything.

Here's a video of the sounds my car makes:

http://www.youtube.com/watch?v=Pz7I5__fHPs

Let me know if you hear anything off.

My Civic has 35K on it. (35,000 miles)

 
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?
you cannot hear it from outside, just inside the car, but your video is from outside?

 
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Sounds like a valve. Try a valve adjustment, hopefully that will fix it.

 
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My phone doesn't pick it up very well inside either, I tried.

@lazlong

I think that's what I'm going to do, gonna look it up in the service manual and get to it.

 
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What you have is called "piston slap." It is a lower end issue that occurs frequently with Civic motors. It is not a valve adjustment problem. What occurs is that there is a small gap between the piston and the chamber that results in this "clacking" sound when the piston "slaps" the chamber wall with it's vertical movement. It should lesson or go away once the engine is warmed up and the metal expands. My '93 does this as well; it has 140K miles on it.

It is my understanding that this really isn't a problem as long as you aren't burning any oil and the compression in the cylinders is okay. All I have been told is that you should take it easy on the motor when the car is cold and once it is warmed up you should be fine. Also, none of the oil/motor/fuel treatments make any difference in terms of eliminating the piston slap, at least in my experience.

Hope this helps.

Bill

 
Rep Power: 313

7th gen Civics arent known for piston slap, they are however known for valve clearance coming out of adjustment. GM 3.4L etc. are known for piston slap